Buick Regal: DTC B263A

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B263A 02

Exterior Illumination Lamp Circuit Short to Ground

DTC B263A 04

Exterior Illumination Lamp Circuit Open

Diagnostic Fault Information

1. Exterior Courtesy Lamps Malfunction

Circuit/System Description

The body control module (BCM) supplies battery voltage to the exterior courtesy LED lighting located under each outside rearview mirror for approach lighting. When the keyless entry transmitter is operated to the lock/unlock functions the exterior door handles LED and the LED lighting located under each outside rearview mirror for approach lighting are commanded ON.

Conditions for Running the DTC

• Battery voltage must be between 9 - 16 V.
• Park lamps ON.

Conditions for Setting the DTC

DTC B263A 02

The BCM detects a short to ground in the exterior courtesy lamps control circuit terminal 8 X7.

DTC B263A 04

The BCM detects an open/high resistance in the exterior courtesy lamps control circuit terminal 8 X7.

Actions Taken When the DTC Sets

The BCM will disable the exterior courtesy lamps control circuit.

Conditions for Clearing the DTC

• The condition responsible for setting the DTC no longer exists.
• A history DTC will clear once 100 consecutive malfunction - free ignition cycles have occurred.

Reference Information

Schematic Reference

Exterior Lights Wiring Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information.

Circuit/System Testing

1. Ignition OFF, all doors closed, all accessories OFF, disconnect the harness connectors at the A9A Outside Rearview Mirror - Driver and the A9B Outside Rearview Mirror - Passenger. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 15 Ω between the appropriate ground circuit terminal 4 and ground.

• If 15 Ω or greater

1. Ignition OFF.
2. Test for less than 2 Ω in the ground circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, repair the open/high resistance in the ground connection.

• Go to next step: If less than 15 Ω

3. Connect a test lamp between the control circuit terminal 17 and ground, ignition ON.

4. Verify the test lamp turns ON and OFF when commanding the Outside Rear View Mirror Courtesy Lamp ON and OFF with a scan tool.

• If the test lamp is always OFF

1. Ignition OFF, disconnect the X7 harness connector at the K9 Body Control Module.
2. Test for infinite resistance between the control circuit and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω in the control circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K9 Body Control Module.

• If the test lamp is always ON

1. Ignition OFF, disconnect the X7 harness connector at the K9 Body Control Module, ignition ON.
2. Test for less than 1 V between the control circuit terminal and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • If less than 1 V, replace the K9 Body Control Module.

• Go to next step: If the test lamp turns ON and OFF

5. Test or replace the appropriate E66 Outside Rearview Mirror Lamps Assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for BCM replacement, programming, and setup.

DTC B2645

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B2645 03

Ambient Light Sensor Circuit Low Voltage

DTC B2645 07

Ambient Light Sensor Circuit High Voltage

Diagnostic Fault Information

1. Daytime Running Lamps Malfunction

Circuit/System Description

The ambient light sensor is used to monitor outside lighting conditions. The body control module (BCM) provides a 5 V reference signal to the ambient light sensor. Depending on outside lighting conditions, the ambient light sensor provides a voltage signal to the BCM that will vary between 0.2 and 4.9 V. The BCM monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for either daytime running lamps or automatic headlamp system control when the headlamp switch is in the AUTO position. In daylight conditions, the BCM will command the daytime running lamps ON by applying voltage to the daytime running lamps control circuits illuminating the daytime running lamps. Any function or condition that turns on the headlamps will cancel daytime running lamps operation.

Conditions for Running the DTC

Battery voltage must be between 9-16 V.

Conditions for Setting the DTC

DTC B2645 03

The BCM detects a short to ground in the ambient light sensor signal circuit.

DTC B2645 07

• The BCM detects a short to voltage or an open/high resistance in the ambient light sensor signal circuit.
• The BCM detects an open/high resistance in the ambient light sensor low reference circuit.

Actions Taken When the DTC Sets

• Automatic headlamp system and daytime running lamps are inoperative.
• The BCM defaults to low light status and commands the low beam headlamps ON.

Conditions for Clearing the DTC

• The condition responsible for setting the DTC no longer exists.
• A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

Headlights/Daytime Running Lights (DRL) Wiring Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

1. Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, open and close drivers door, disconnect the harness connector at the B10B Ambient Light/Sunload Sensor. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 15 Ω between the low reference circuit terminal 6 and ground.

• If 15 Ω or greater

1. Ignition OFF, disconnect the X2 harness connector at the K33 HVAC Control Module.
2. Test for less than 2 Ω in the low reference circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K33 HVAC Control Module.

• Go to next step: If less than 15 Ω

3. Ignition ON.

4. Verify the scan tool Ambient Light Sensor parameter is greater than 4.65 V.

• If 4.65 V or less

1. Ignition OFF, disconnect the X2 harness connector at the K9 Body Control Module.
2. Test for infinite resistance between the signal circuit terminal 3 and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • If infinite resistance, replace the K9 Body Control Module.

• Go to next step: If greater than 4.65 V

5. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the low reference circuit terminal 6.

6. Verify the scan tool Ambient Light Sensor parameter is less than 0.196 V.

• If 0.196 V or greater

1. Ignition OFF, disconnect the X2 harness connector at the K9 Body Control Module, ignition ON.
2. Test for less than 1 V between the signal circuit terminal 3 and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • Go to next step: If less than 1 V
3. Test for less than 2 Ω in the signal circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K9 Body Control Module.

• Go to next step: If less than 0.196 V

7. Test or replace the B10B Ambient Light/Sunload Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Sun Load Temperature and Headlamp Automatic Control Ambient Light Sensor Replacement
• Control Module References for BCM replacement, programming, and setup

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